Method for producing coffee extract

ABSTRACT

A method for manufacturing a coffee extract is provided which method enables flavor ingredients of coffee to be extracted separately from bitter ingredients. A coffee extract is obtained by a method including a) a step of placing coffee granules in a granule container part substantially sealed by a restraining member, b) a step of guiding an extraction solvent from a first direction into the granule container part for extraction, and c) a step of retrieving, from the first direction, a coffee extract stored in the granule container part.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a coffeeextract, in which excessive scorched bitterness involved in the roastingof coffee beans is reduced.

BACKGROUND ART

Commonly coffee beverages include coffee extracts extracted, using hotwater or water, from granules into which roasted coffee beans are ground(hereinafter referred to as coffee granules). The coffee beverage isknown to contain more than 300 types of flavor ingredients and about 10types of nutrient ingredients and serves not only as a tasty beveragebut also as a beverage with nutrient function claims. Thus, obtaining acoffee extract liquid with an excellent flavor is important forcontinuing to drink coffee beverages in everyday life for a long period.

A concentrated coffee extract is known as a coffee extract with anexcellent flavor. The concentrated coffee extract refers to the firstseveral thick droplets of coffee during extraction. It has been reportedthat the concentrated coffee extract is a thick and flavory coffeeliquid which gives a thick texture on the tongue and which has anexcellent aftertaste that disappears cleanly and that the best coffee isobtained by making the most of the attractive characteristics of theconcentrated coffee extract (see Non-Patent Literature 1).

In general, methods for extracting coffee are roughly classified into afiltering method (drip type), a steeping method (stirring or boilingtype), and an espresso method (vaporization type). For each of theextraction methods, various methods for obtaining a coffee extract withan excellent flavor have been proposed. For example, a steeping method(see Non-Patent Literature 2) involves limiting the amount of hot waterand leaving a coffee extract unchanged for a specific time, and a methodinvolves filling coffee granules into a glass pipe with opposite endsthereof open and slowly dripping cool water in a glass container intothe glass pipe from above to collect eluate in the glass container overa long time (this type of coffee is called Dutch Coffee, cold-brewcoffee, or drip coffee).

Furthermore, methods have been reported which suppress extraction ofoffensive ingredients to improve the flavor of the coffee extract. Forexample, a method involves filling coffee granules into an extractor,injecting hot water into the extractor from below the extractor, mixingthe coffee granules with the hot water, and then allowing a coffeeextract to flow out from the bottom of the extractor. This method hasbeen disclosed to sufficiently stir and mix the coffee granules and theextraction solvent (hot water), enabling a reduction in time needed forextraction and thus a reduction in offensive ingredients such asharshness or astringency in a coffee bean which have been eluted in theextract liquid as a result of the long extraction (see PatentLiteratures 1 and 2).

Moreover, methods for selectively removing offensive ingredients toimprove the flavor of the coffee extract have also been reported. Forexample, a method involves selectively adsorbing and removingmacromolecular brown-black ingredients such as chlorogenic acid polymerswhich make the coffee extract astringent, utilizing, as an adsorbent,activated carbon with an average pore radius distributed in theneighborhood of 30 to 100 Å (Patent Literature 3). Another methodinvolves mixing an oxygen treatment with an adsorption treatment withactivated carbon, PVPP, activated white earth or the like to reduce thebitterness and astringency of tannin, caffeine, or the like (PatentLiterature 4).

On the other hand, it is known that roasting coffee beans allows ahoneycomb structure to be formed. Partition walls of the honeycombstructure have been reported to have a large surface area comparable tothe surface area of a porous gel and thus to have an ingredientadsorptive capacity (see Non-Patent Literature 3).

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Laid-Open No. 01-148152-   Patent Literature 2: Japanese Patent Laid-Open No. 2004-16586-   Patent Literature 3: Japanese Patent No. 2578316-   Patent Literature 4: Japanese Patent Laid-Open No. 2003-310162

Non-Patent Literature

-   Non-Patent Literature 1: Yukio Hirose et al., Kohigaku Kougi    (Lecture on Science of Coffee), Ningen No Kagakusha (Tokyo), 2003-   Non-Patent Literature 2: Makoto Takagi, Kohibunka Kenkyu (Study of    Coffee Culture), 15, pp. 113-134, 2008-   Non-Patent Literature 3: M. R. Jisha, et al., Mater. Chem. Phys.,    115, pp. 33-39, 2009

SUMMARY OF INVENTION Technical Problem

Attempts have conventionally been made to reduce bitterness andastringency, which are offensive ingredients. However, in some cases,bitterness is successfully sufficiently removed, whereas astringencyfails to be sufficiently removed, or in other cases, both bitterness andastringency are successfully removed but a rich fragrance, a flavor, anda rich taste unique to coffee are simultaneously removed to degrade theflavor of the coffee extract itself.

An object of the present invention is to provide a method formanufacturing a coffee extract which method allows a selective reductionin an excessively bitter taste with preferable flavor ingredients ofcoffee unchanged. Another object of the present invention is to providea method for manufacturing a coffee extract with an excellent flavor forwhich excessive bitterness and astringency are selectively reduced withpreferable flavor ingredients of coffee unchanged.

Solution to Problem

As is known with the concentrated coffee extract, the surface of roastedbeans has more aroma ingredients than the interior of the roasted coffeebeans, thus allowing a flavory extract liquid to be efficiently obtainedwith a small amount of extract. However, bitter ingredients producedduring the final stage of roasting are adsorbed on the outermost surfaceof the coffee beans. Thus, an extract liquid of the surface of theroasted beans gives an excessively bitter taste (sometimes referred toas “scorched bitterness”), and thus, obtaining a coffee extract withacidity, bitterness, and rich taste balanced is difficult.

The present inventors have earnestly studied methods for selectivelyremoving scorched bitterness from an extract liquid of the surface ofroasted beans, as methods for solving the above-described problem. As aresult, the present inventors have found that the ingredients which showscorched bitterness has a strong affinity for partition walls of thehoneycomb structure of the coffee beans. The present inventors havefurther found that a coffee extract can be obtained by utilizing theaffinity to adsorb the scorched bitter ingredient on the partition wallsof the coffee beans to separate the scorched bitter ingredient byplacing coffee granules in a granule container part substantially sealedby a restraining member and passing an extraction solvent through alayer of accumulated coffee granules in such a manner that theextraction solvent reciprocates through the layer. Thus, the presentinvention has been completed. That is, the present invention relates tothe following.

1. A method for manufacturing a coffee extract, the method including:

a) a step of placing coffee granules in a granule container partsubstantially sealed by a restraining member;

b) a step of guiding an extraction solvent from a first direction intothe granule container part for extraction; and

c) a step of retrieving, from the first direction, a coffee extractstored in the granule container part.

2. The method set forth in 1, wherein, in step c), the coffee extract isretrieved by guiding water from a second direction opposite to the firstdirection.3. The method set forth in 1 or 2, wherein, in step c), the extractliquid is retrieved in such a manner that an extraction rate is 20% orless.4. The method set forth in any one of 1 to 3, wherein the restrainingmember is a mesh member.5. The method set forth in any one of 1 to 4, wherein the coffeegranules are accommodated so as to accumulate in such a manner that thecoffee granules have a substantially rectangular cross-sectional shapein a direction along an axis.6. The method set forth in any one of 1 to 5, wherein the restrainingmember is positioned in abutting contact with or in close proximity to asurface of deposited layers of the coffee granules which is opposite tothe first direction.7. The method set forth in any one of 1 to 6, wherein the firstdirection is on a lower side of the deposited layers of the coffeegranules.8. The method set forth in any one of 1 to 7, wherein, in step b), theextraction solvent is injected up to a position substantially aligningwith a top surface of the deposited layers of coffee granules.

Advantageous Effects of Invention

The method for manufacturing according to the present invention allowseasy obtainment of a coffee extract with a very excellent flavor(particularly a coffee extract of the surface of roasted beans) with theflavor and rich taste of coffee maintained and with only the excessivelybitter taste of coffee reduced. Thus, for example, unprecedented coffeecan be manufactured which has a clean finish and significantly exhibitsthe characteristics of coffee beans themselves even if the coffee is asthick as or thicker than espresso. Furthermore, the coffee extractobtained by the method for manufacturing according to the presentinvention has the advantages of being clear and having high preservationstability.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual drawing of behavior of ingredients in a methodfor manufacturing according to the present invention.

FIG. 2 is a diagram showing an example of an extraction device that canbe used for a method for manufacturing according to the presentinvention (coffee extraction device 1).

FIG. 3 is a diagram showing a circular filter with a diameter of 45 mm(FIG. 3A) and a restraining member 11 (FIG. 3B).

FIG. 4 is a diagram showing a mode in which deposited layers of coffeegranules M is wholly covered with a nonwoven cloth that is therestraining member, that is, a granule container part 2 with abag-shaped restraining member.

FIG. 5 is a diagram of a case where the restraining member 11 is in theform of a lid member.

FIG. 6 is a diagram of a coffee extraction device 1 which is similar tothe coffee extraction device in FIG. 2 and which includes an opening 2Aformed at an upper end of the granule container part 2 which endcorresponds to a direction opposite to a first direction and a conduitchannel 5′ connected to the opening 2A to guide water to the opening 2A.

FIG. 7 is a diagram illustrating a coffee extraction device used in TestExample 1.

FIG. 8 is a diagram illustrating the coffee extraction device used inTest Example 1.

FIG. 9 is a diagram illustrating a coffee extraction device used inExample 4.

FIG. 10 is a diagram in which the logarithms of the relativeconcentrations of ingredients are plotted for each fraction.

FIG. 11 is a diagram showing the results of analysis of caffeine.

FIG. 12 is a diagram showing the results of analysis of chlorogenicacid.

FIG. 13 is a diagram showing the results of measurement of turbidityusing extracts obtained using a CC method, a CD method, and a PD method.

DESCRIPTION OF EMBODIMENTS

When coffee beans are roasted, moisture is evaporated from the coffeebeans. The internal cell tissues of the coffee beans are hollowed tohave a honeycomb structure. Carbon dioxide, aroma ingredients, tasteingredients (water-soluble taste ingredients), and the like in coffeeare adsorbed on the protruding and recessed surfaces (partition walls)of the hollowed cell membranes. According to the present method formanufacturing, a small amount of extraction solvent is passed throughthe aroma ingredients and taste ingredients (water-soluble tasteingredients and bitter ingredients) adsorbed on the surface of thehoneycomb structure, to temporarily desorb the aroma ingredients and thetaste ingredients to expose the surface of the honeycomb structure.Scorched bitter ingredients, included in the desorbed ingredients, arethen selectively caught (resorbed) and thus removed in a separablemanner. The greatest characteristic of the method for manufacturingaccording to the present invention is that roasted coffee beans with thesurface of the honeycomb structure exposed are utilized as an adsorbent.

The present invention consecutively carries out a step of exposing thesurface of the honeycomb structure and a step of adsorbing scorchedbitterness on the exposed honeycomb structure without the need for acumbersome operation. Specifically, the present invention adopts amethod of passing an extraction solvent through a layer of coffeegranules packed (fixed) in a substantially sealed manner so that theextraction solvent reciprocates through the layer. When coming into thefirst contact with the coffee granules (forward path), the extractionsolvent temporarily desorbs the aroma ingredients and taste ingredients(water-soluble taste ingredients and bitter ingredients) adsorbed on thesurface of the honeycomb structure to expose the surface of thehoneycomb structure. The extraction solvent containing the desorbedingredients is brought into contact with the coffee granules with thesurface of the honeycomb structure exposed to selectively resorb onlythe bitter ingredients in the extraction solvent (see FIG. 1).

The “reciprocation of the extraction solvent” as used herein refers tothe flow of the extraction solvent in which, for example, the extractionsolvent reciprocates in the direction of gravity or a horizontaldirection with respect to the layer of the coffee granules, and meansthat the extraction solvent temporarily flows in one direction andsubsequently in the opposite direction. For example, the reciprocationof the extraction solvent refers to the flow of water (extractionsolvent) in which if the extraction solvent guided in to desorb theingredients adsorbed on the honeycomb structure flows in anantigravitational direction through the coffee granule layer, an extractliquid of the surface of the resultant roasted beans flows in thedirection of gravity.

The method for manufacturing according to the present invention will bedescribed below in connection with specific embodiments based on thedrawings. However, the present invention is not limited to theseembodiments.

FIG. 2 shows a coffee extraction device 1 in a vertical orientation. Thecoffee extraction device 1 includes a granule container part 2 with anupper opening 2A formed at an upper end thereof, a lower opening 2B(which serves both as an injection port and as a takeout port) formed ata lower end thereof, and an extraction section E storing coffee granulesM, a lid member 3 that can be freely installed on and removed from theupper opening 2A, a conduit channel 8 that is in communication with thelower opening 2B in the granule container part 2, an extraction solventtank 4, a supply channel 5 that injects the extraction solvent from theextraction solvent tank 4 into the lower opening 2B, and a liquid feedchannel 7 that transfers a coffee extract from the lower opening 2B to astorage tank 6. The conduit channel 8 is connected to the supply channel5 and the liquid feed channel 7 by a three-way valve 9.

(Step a)

When the apparatus shown in FIG. 2 is used, first, coffee granules areplaced in the extraction section E so as to be substantially sealed by arestraining member according to the present method for manufacturing. Asdescribed above, the present invention utilizes roasted coffee beanswith the surface of the honeycomb structure exposed as an adsorbent. Tomake the most of the effects of the adsorbent, it is important toaccommodate coffee granules in the granule container part in asubstantially sealed manner. The term “substantially sealed” as usedherein refers to a state in which, when the extraction solvent is passedthrough the coffee granules, the coffee granules are prevented frommoving around inside the granule container part and means that thedeposited layers of the coffee granules are enclosed by walls of thegranule container part, a filter member, the lid member and the like. InFIG. 2, a lower filter member 10 (first filter medium) is installed onthe lower side of the granule container part 2 (in a first direction),coffee granules M are accommodated on an upper surface of the lowerfilter member 10, and a restraining member (second filter member) 11 ispositioned in abutting contact with or in close proximity to an oppositesurface (uppermost surface) of the deposited layers of the coffeegranules M. That is, the coffee granules M are accommodated in theextraction section E of the granule container part 2 in a substantiallysealed manner by a right wall surface and a left wall surface present ina direction along the axis of the granule container part 2, the lowerfilter member 10, and the restraining member 11. In the specification,the extraction section E corresponds to a portion of the coffee granulecontainer part 2 in which the coffee granules M are accommodated in asubstantially sealed manner, that is, the interior of an area betweenthe position of the lower filter member 10, provided at the lower endposition of the granule container part 2, and the position of therestraining member 11, removably provided above the lower filter memberso as to internally contact the granule container part 2.

The coffee granules M, an extraction material according to the presentinvention, may be granules obtained by grinding roasted coffee beans. Atree species grown for the coffee beans is not particularly limited andmay be, for example, an Arabica species or a Robusta species. The methodaccording to the present invention is characterized by obtaining acoffee extract having a clean finish even when the coffee is thick andexhibiting significant characteristics, and using much of the Robustaspecies leads to an excessively emphasized Robusta smell. Thus,particularly the Arabica species is preferably used. Furthermore, thecoffee brand is not particularly limited and may be, for example, Mocha,Brazil, Columbia, Guatemala, Blue Mountain, Kona, Mandheling, orKilimanjaro. A plurality of coffee brands may be blended together to beused.

The degree of roasting (normally expressed as light roast, medium roast,and extra roast in order of increasing degree of roasting) is also notparticularly limited. In general, coffee beans roasted at the lightlevel and at the extra level are known to have the following features.Coffee beans roasted at the light level fail to exhibit the richcharacteristics of the coffee beans themselves, and serve to reduce ascorched smell resulting from roasting but are not heated up to theinterior of the beans and tend to give an unfavorable taste or an acidtaste. Coffee beans roasted at the extra level serve to increase ascorched smell on the surface, but give a bitter taste which is uniqueto coffee and which results from roasting as well as a spicy fragrancerising therefrom, leading to an attractive flavor. The medium roast andthe extra roast are preferred because these types of roasts serve tomake the most of the characteristic of the present invention that thepresent invention produces a coffee extract with scorched bitternessrestrained and significant characteristics exhibited. In terms of an Lvalue, the range from 15 to 24 is preferable, the range from 16 to 22 ismore preferable, and the range from 16 to 20 is particularly preferable.The L value is a numerical value for the surface color of coffeegranules into which roasted coffee beans are ground and is indicative oflightness (0 is indicative of black, and 100 is indicative of white).The L value of the coffee granules can be measured using, for example, acolor-difference meter. The use of coffee beans roasted at the extralevel also advantageously improves the efficiency of extraction ofnutrient ingredients.

The degree of grind of roasted coffee beans (normally classified intocoarse grind, medium grind, fine grind and the like) is not particularlylimited, and ground beans with different grain size distributions can beused. However, an excessively low degree of grind is likely to cause thefirst filter member to be clogged, increasing time needed for extractionto cause over-extraction. Thus, in particular, the medium grind and/orthe coarse grind is a preferred aspect of the present invention. Interms of average grain size after grind, the range from about 0.1 mm toabout 2.0 mm is preferable, the range from about 0.5 mm to about 2.0 mmis more preferable, and the range from about 1.0 mm to about 1.5 mm isparticularly preferable. The term “over-extraction” as used hereinrefers to a phenomenon in which the extraction solvent comes intoexcessive contact with the coffee granules to extract an astringenttaste and an unfavorable taste from inside the coffee beans.

The first filter member is installed in order to prevent the coffeegranules from falling and mixing into the coffee extract. Any filtermember that meets this object may be used. Specific examples of thefirst filter member may be mesh members such as a metal mesh, a nonwovencloth (e.g. flannel cloth or lint cloth), and a paper filter. A filtermember with an excessively small mesh size is likely to be clogged,increasing time needed for extraction to cause over-extraction. Thus,for a metal mesh, the mesh size is preferably about 20 to about 200 interms of American mesh size. Furthermore, a nonwoven cloth is preferablyused because the nonwoven cloth can adsorb and remove oil contained inthe coffee extract.

In step b described below, the coffee granules M are deposited andaccommodated in the granule container part 2 shaped to have anapproximately uniform inner diameter in the advancing direction (in FIG.1, the antigravitational direction (down-up direction)) of theextraction solvent so that the extraction solvent comes into evencontact with the coffee granules M. That is, the coffee granules M aredeposited in the form of a cylinder or a rectangular parallelepiped(including a cubic) so as to have a substantially rectangularcross-sectional shape in a direction along the axis of the depositedlayers of the coffee granules M. The present invention utilizes thecoffee granules as an adsorbent, and the shape (the relation between thecross-sectional area and the height) of the extraction section E isimportant in making the most of the adsorption effect. Althoughdepending on the characteristics of the coffee granules such as thegrain size, the coffee granules M are generally preferably accommodatedin the extraction section E so that, in a substantially rectangularcross-sectional shape in the direction along the axis of the extractionsection E, the ratio (H/L) of the width (L) to height (H) of therectangle is in the range of 0.1 to 10, preferably 2 to 6, and morepreferably 3 to 6. Above these ranges, the extraction may take much timeor clogging may occur, leading to over-extraction. Furthermore, belowthe ranges, the adsorption effect of the present invention may notsufficiently be produced.

In FIG. 2, the restraining member 11, removably positioned above thelower filter member so as to internally contact the granule containerpart 2, allows the coffee granules M to be accommodated in asubstantially sealed manner. Normally, during coffee extraction, thecoffee granules move around (flows) in response to injection of theextraction solvent. For example, in the drip extraction, the coffeegranules float up close to the liquid surface or move along the paththrough which the extraction solvent is injected. In the steepingextraction, the coffee granules float up close to the liquid surface orflow swiftly due to natural convection or stirring. According to thepresent invention, the restraining member 11 is positioned in abuttingcontact with or in close proximity to the uppermost surface of thecoffee granules M to hold the coffee granules M in a substantiallysealed manner. This prevents the coffee granules from moving aroundduring extraction. The coffee granules prevented from moving aroundenable the target bitter ingredient to be resorbed on the partitionwalls of the exposed coffee honeycomb structure.

Thus, the material, shape, and the like of the restraining member 11 arenot particularly limited provided that the restraining member 11 canhold the coffee granules M in a substantially sealed manner andinternally contact the granule container part 2. An example of therestraining member may be a mesh member (hereinafter sometimes referredto as a second filter member) similar to mesh member of the first filtermember. If a mesh member is used restraining member, then preferably aperipheral portion of the mesh member is formed of an elastic material(for example, cotton flannel) and the restraining member 11 is broughtinto pressure contact with the inner surface of the granule containerpart 2 to enhance the braking function (see FIG. 3). Furthermore, FIG. 4shows a mode in which the whole deposited layers of the coffee granulesM are covered with a nonwoven cloth serving as the restraining member,that is, the granule container part 2 with a bag-shaped restrainingmember. In this mode, the first filter member and the second filtermember are not distinguished from each other, and the restraining memberfunctions as the first filter member. Moreover, it is assumed that thepresent invention includes a mode in which the restraining member 11 isin the form of a lid member as shown in FIG. 5.

The restraining member is positioned in abutting contact with or inclose proximity to the uppermost surface of the deposited layers of thecoffee granules M in a dry state so as to substantially seal the coffeegranules M. The position where the restraining member 11 is in closeproximity to the coffee granules M refers to a position where, when thecoffee granules M are wetted with the extraction solvent, therestraining member is separated from the uppermost surface of thedeposited layers of the coffee granules M by a distance corresponding tothe amount of natural bulging (void) of the coffee granules.Specifically, the position refers to the interior of the area betweenthe position where the coffee granules are slightly compressed (so as toreduce the volume of the coffee granules to about nine-tenths) and aposition which corresponds to the approximately doubled volume of thecoffee granules (preferably the original volume multiplied by about 1.5)and which is used taking into account the bulging of the coffee granulesafter contact with the extraction solvent.

(Step b)

Subsequently to step a described above, the extraction solvent is guidedinto the extraction section E for extraction from the first direction(step b). In the apparatus shown in FIG. 2, the “first direction” asused herein is shown as the lower side of the deposited layers of thecoffee granules.

The present inventors have confirmed that the method for manufacturingaccording to the present invention is effective in reducing scorchedbitterness at any temperature of the extraction solvent. However, anelevated temperature of the extraction solvent allows the richfragrance, flavor, and rich taste unique to coffee to be moreappropriately extracted and also allows the rich characteristics ofcoffee beans themselves to be more appropriately exhibited. Thus, waterat 15° C. to 10° C. or preferably hot water at 50° C. to 98° C. ispreferably used as the extraction solvent. In particular, the presentinventors have confirmed that the use of hot water at 60° C. to 95° C.allows a coffee extract with a strong odor and a sweet taste to beobtained.

In step b, water (preferably hot water) is brought into contact with thecoffee granules M placed in the granule container part in asubstantially sealed manner in step a) to temporarily desorb theingredients (aroma ingredients and taste ingredients produced mainlyduring roasting) adsorbed on the partition walls of the honeycombstructure of roasted coffee beans. Thus, the surfaces of the partitionwalls of the honeycomb structure are exposed. That is, preparation ismade to carry out efficient separation of bitter ingredients utilizingthe coffee granules as an adsorbent, which is characteristic of thepresent invention.

Any amount of extraction solvent may be passed in step b provided thatthe amount enables the ingredients adsorbed on the partition walls ofthe honeycomb structure to be temporarily desorbed. The amount is equalto the volume of the coffee granules M multiplied by about 0.3 to about2 or preferably about 0.5 to about 1.5 or is more preferably such thatthe extraction solvent is injected substantially up to the upper surfaceof the deposited layers of the coffee granules M. In step b, the use ofa small amount of extraction solvent can produce an extract liquid ofthe surface of the roasted beans having rich aroma ingredients and richtaste ingredients. Feeding an amount of extraction solvent exceeding theabove-described range may reduce the efficiency with which scorchedbitter ingredients are separated in step c described below or may causean unfavorable taste to be extracted from inside the coffee beans todegrade the flavor of the extract. The amount of extraction solventinjected may be controlled by a level gauge provided in the granulecontainer part or calculated from the volume of the coffee granulelayer. An example of a calculation is illustrated below. In general, thebulk specific gravity of coffee granules resulting from the medium roastand medium grind is 0.3 to 0.5. For example, if 10-g coffee granules arefilled into a glass pipe with an inner diameter of 55 mm, the volume ofthe extraction section is approximately 25 mL, and the volume of theextraction solvent needed to fill the extraction section up to the uppersurface thereof is 15 mL per 10-g granules.

The extraction solvent the amount of which falls within theabove-described range is passed through the granule container part 2 ata velocity SV (Space Velocity)=about 3 to about 100. Then, theingredients adsorbed on the coffee granules M can be effectivelydesorbed. A more preferable liquid passage rate SV is about 5 to about70, preferably about 5 to about 50, or more preferably about 6 to about40.

(Step c)

In step c, the extraction solvent (water or preferably hot water) isbrought into contact with the coffee granules. Then, it is expected thatstrong bitter ingredients produced during the final stage of roastingand adsorbed on the uppermost surface of the partition walls are firstdesorbed and that a solution containing a high concentration of theseingredients is temporarily transferred toward a direction opposite tothe first direction (in FIG. 2, the upper side of the deposited layersof the coffee granules M) (see FIG. 1( b)). The resultant coffee extractis retrieved from the direction opposite to the first direction towardthe first direction (step c). It is expected that the coffee extractpasses through the deposited layers of the coffee granules M with thepartition walls of the honeycomb structure exposed, allowing theexcessively bitter ingredients to be resorbed on the partition walls ofthe honeycomb structure for separation (see FIGS. 1( c) and 1(d)).

Means for retrieving the coffee extract from the first direction is notparticularly limited. Examples of the means include (i) a method ofretrieving the coffee extract by suction with a pump or the like fromthe first direction (in FIG. 2, the lower side of the extractionsection), (ii) a method of retrieving the coffee extract by introducingair or the like from the direction opposite to the first direction (inFIG. 1, the upper side of the extraction section) to pressurize thecoffee extract, that is, retrieving the coffee extract bypressurization, and (iii) a method of retrieving the coffee extract byinjecting water from the direction opposite to the first direction (inFIG. 2, the upper side of the extraction section) to push the coffeeextract (this method is hereinafter sometimes referred to as “waterdrive”). The pressurization methods (methods (i) and (ii)) may causebitter ingredients adsorbed on the partition walls to be desorbeddepending on the magnitude of the pressure. Thus, the method ofretrieving the coffee extract by water drive is simple and easy and is apreferred aspect.

FIG. 6 shows a coffee extraction device 1 which is similar to the coffeeextraction device in FIG. 2 and which includes an opening 2A formed atan upper end of a granule container part 2 which end corresponds to thedirection opposite to the first direction and a conduit channel 5′connected to the opening 2A to guide water to the opening 2A. The methodof retrieving the coffee extract by water drive will be described indetail based on FIG. 6. Coffee granules are accommodated in anextraction section E of the cylindrical granule container part 2 in avertical orientation so that an upper surface and a lower surface of thecoffee granules M are pressed by the respective filters to substantiallyseal the coffee granules M. An operation of opening a three-way valve 9is performed to inject an extraction solvent (water or preferably hotwater) from a medium tank 4 (for example, a hot water tank) to theopening 2B. Thus, the extraction solvent is filled from the lower sideof the deposited layers of the coffee granules M substantially up to theupper surface of the deposited layers of the coffee granules M. At thistime, no extract liquid is retrieved until the extraction solventsubstantially reaches the upper surface of the deposited layers of thecoffee granules M, maintaining a silent hold state. When the extractionsolvent is injected up to a predetermined position, an operation ofopening a supply valve 5A′ is performed to inject the extraction solvent(water or preferably hot water) from the extraction solvent tank 4 tothe upper opening 2A in the granule container part 2 via an opening 3Aformed in a lid part 3. Then, a coffee extract is retrieved through thelower opening 2B in the granule container part 2 by water drive. Thetemperature and the like of the water injected through the opening 2Aare not particularly limited provided that the water can be used forwater drive.

The present inventors' studies indicate that bitter ingredients have thefollowing property. That is, the bitter ingredients adsorbed on theuppermost surface of the partition walls during roasting are easilydesorbed by being brought into contact with water (particularly hotwater), but the bitter ingredients resorbed on the exposed partitionwalls of the honeycomb structure have a strong affinity for thepartition walls and are unlikely to be desorbed even when brought intocontact with hot water. In general, an extraction residue of the coffeegranules is expected to contain extract liquid ingredients which havethe same concentration as that of extract liquid ingredients in thecoffee extract and which are equivalent to or larger than residualsolids in amount. Thus, extract liquid ingredients contained in theextraction residue of the coffee granules can be efficiently extractedby retrieving, by water drive, an extract liquid of the surface of theroasted beans obtained in step a and then continuing to inject theextraction solvent (water) into the extraction section E through theopening 2A to continue the extraction with the water. Thus, thetemperature or amount of water injected through the opening 2A may beset as appropriate depending on the purpose of retrieving an extractliquid of the surface of the roasted beans by water drive or extractingextract liquid ingredients from the extraction residue of the surface ofthe roasted beans. The temperature of the water may be changed instages. For the purpose of extracting extract liquid ingredients with anexcellent flavor from the extraction residue of the surface of theroasted beans, the temperature of water guided from the second directionaccording to the present invention is 15° C. to 100° C., preferably 50°C. to 98° C., or more preferably 60° C. to 95° C.

The present inventors' examinations indicate that unfavorableingredients of the coffee extract include not only excessively bitteringredients (scorched bitterness) adsorbed on the uppermost surface ofthe partition walls of the coffee beans but also astringent ingredientseluted during the middle and last periods of extraction and left on thetongue. In step c, in the method of retrieving a coffee extract by waterdrive, a coffee extract with a better flavor can be efficiently obtainedby controlling the extraction such that the retrieval of the astringentingredients is avoided which are eluted during the middle and lastperiods of extraction and which are left on the tongue. Specifically,the sampled amount of coffee extract retrieved through the lower opening2B in the granule container part 2 by water drive is equal to the volumeof the coffee granules M multiplied by about 0.5 to about 5, preferablyabout 1 to about 3, or more preferably about 1 to about 2. When thesampled amount is more than five times as large as the volume of thecoffee granules M, the astringent ingredients in the extract liquid areperceived.

Such extraction results in a coffee extract extraction rate of 20% orless or preferably 15% or less.

Coffee extraction rate (%)={weight of extract (g)}×{Brix of extract(%)}/{weight of coffee granules (g)} (Brix is indicative of solublesolids measured with a refractometer. An example of the refractometermay include a digital refractometer RX-5000α manufactured by ATAGO CO.,LTD.)

In step c, the coffee granules with the surface of the partition wallsof the honeycomb structure exposed are used as an adsorbent and anextract liquid of the flavory surface of the roasted beans obtained instep b is passed through the coffee granules to resorb scorched bitteringredients in the extract liquid on the coffee granules. In this case,for efficient adsorption, the liquid passage rate is important. In stepc, the velocity (SV (Space Velocity) at which the extraction solvent ispassed through the coffee granules is preferably about 3 to about 100,more preferably about 5 to about 70, further more preferably about 5 toabout 50, or particularly preferably about 6 to about 40.

In step b, when the extraction solvent is injected into the extractionsection E, bubbles sealed in the coffee granules are released into theextraction section E, in which the bubbles stay. The flow velocity ofthe extract liquid is significantly impacted by the bubbles present inthe extraction section E. Thus, the bubbles in the extraction sectionare preferably removed before step c and/or simultaneously with step cin order to facilitate the control of the flow velocity and to preventastringent ingredients from being eluted (over-extracted) due to anexcessively long time needed for extraction. Means for removing thebubbles in the extraction section is not particularly limited. Theextraction section may be degassed by a publicly-known method before orafter the coffee granules are placed in the granule container part 2.Examples of the publicly-known degassing method include a decompressionprocess, a method of carrying out degassing by applying a physicalstimulus such as vibration to the extraction section E, a method ofcarrying out degassing by ultrasound, and a method of carrying outdegassing using an inserted degassing pipe. The present inventors haveconfirmed that when the column of the extraction section is slightlyvibrated from outside the extraction section using a commerciallyavailable handy vibrator (THRIVE (registered trade mark) manufactured byDAITO ELECTRIC MACHINE INDUSTRY CO., LTD.), bubbles in the granule layermove upward and are removed from the mesh member 11.

In the method for manufacturing a coffee extract according to thepresent invention, water (preferably hot water) passes, in areciprocating manner, through the layer of the coffee granules depositedin a substantially sealed manner. That is, water (preferably hot water)is passed from the first direction to the opposite direction (seconddirection) and then discharged from the second direction toward thefirst direction. The first amount of coffee extract discharged from theextraction section has not substantially passed through the layer of thecoffee granules, and is thus a very dilute solution. Preferably, anextract liquid is retrieved after the first solution is disposed of.However, the first solution does not contain any bitter ingredient orany astringent ingredient, which is left on the tongue, and may thus beretrieved along with the subsequent extract. The liquid discharged asthe dilute solution is a liquid discharged during the very initialperiod of extraction and corresponding to an extraction rate of about1%.

EXAMPLES

The present invention will be described below in detail based onexamples. However, the present invention is not limited to the examples.

Test Example 1

FIG. 7 is a diagram illustrating a coffee extraction device 1 accordingto an embodiment of the present invention which was used in TestExample 1. The coffee extraction device 1 includes a substantiallycylindrical granule container part 2 with an upper opening and a loweropening (2A and 2B) (the inner diameter of the upper opening: 55 mm andthe length of the upper opening: 250 mm), and has an extraction pipe(glass pipe/chromatography pipe) 8 formed at a lower end of the granulecontainer part 2 and having a three-way cock, and a hot water container(glass pipe) 4 having an inner diameter of 50 mm and a length of 100 mmand connected to the three-way cock 9 of the extraction pipe 8 via atube 5.

A filter 10 was installed in a bottom portion of the granule containerpart 2, and 40-g coffee granules (Arabica coffee beans grown in Ethiopiaand roasted in an Italian manner were ground at the medium level) wereplaced on an upper surface of the filter 10. A restraining member 11 forbraking the flow of the coffee granules was placed slightly away from anupper surface of the deposited layers of the coffee granules (placed ata position where, when the coffee granules are bulged as a result ofcontact with an extraction solvent, the upper surface of the depositedlayers of the bulged coffee granules comes into abutting contact withthe restraining member 11). The filter 10 was a circular filter (FIG.3A) with a diameter of 45 mm including six lint clothes sewed togetherin an overlapping manner, an O ring sealed in the sewed lint clothes andformed of wire with a diameter of 1 mm and having a diameter of 35 mm,and an appropriate amount of small pieces of lint cloth sealed in thesewed lint clothes so as to increase the thickness of a central portionthereof. The restraining member 11 included a ring member having anouter diameter of 58 mm and an inner diameter of 37 mm and including anO ring formed of wire with a diameter of 1 mm and having a diameter of47 mm and sewed on eight overlapping ring-like lint clothes, an innerdiameter portion of the ring member being sealed with (a piece of)cotton gauze (FIG. 3B).

With the three-way cock 9 closed, 100-mL hot water (95° C.) was added tothe hot water container 4. A lower tip of the hot water container 4 wasfitted into an upper end (the position of the restraining member 11) ofan extraction section E, and an operation of opening the three-way cock9 was performed to inject hot water from the lower side of the apparatus(first direction) into the extraction section E (FIG. 8A). When asurface of the hot water flowing upward through the granule layer in theextraction section E comes into contact with the restraining member 11,the cock 9 was closed and subsequently 400-mL hot water (90° C.) wasinjected toward the extraction section E through the upper opening 2A,located on the upper side of the deposited layers of the coffee granules(second direction) (FIG. 8B). An operation of opening the cock 9 wasperformed to retrieve and inject an outflow coffee extract into a 100-mLgraduated cylinder (FIG. 8C). When bubbles generated during extractioncaused clogging, an aligning string 1 g attached to the restrainingmember 18 was operated to remove bubbles. Thus, outflow velocity wasadjusted. The extract liquid was fractionated into 20-mL fractions, and12 fractions were retrieved. Then, a 0.5-mL extract liquid of eachfraction was placed in an NMR measurement pipe, and 0.58-mmol TSP-d4(3-(trimethylsilyl)propionic-2,2,3,3-d₄ acid sodium salt) was added asan internal standard substance, to the extract, which was then stirredwell. Measurement was carried out by a 1D-NOESY-presaturation pulsesequence technique using a nuclear magnetic resonance apparatus (Avance600 apparatus manufactured by Bruker Biospin in Switzerland). Then, thestandard signal of TSP-d4 and the particular signal of each ingredientwere compared with each other in terms of height, the signals beingobserved at a chemical shift 0.00 ppm in an NMR spectrum. The particularsignals of the respective ingredients were a singlet at 3.23 ppm forcaffeine, a singlet at 1.95 ppm for acetate salt, a singlet at 8.45-ppmfor formate, a singlet at 9.11 ppm for trigonellin, a doublet at 8.79ppm for N-methyl pyridinium cation, a singlet at 8.95 ppm for nicotineacid, and a singlet at 9.65 ppm for a bitter ingredient with an unknownstructure. The ratio of each of these signal heights to the signalheight for TSP-d4 was determined to be the relative concentration of thecorresponding ingredient relative to the internal standard TSP-d4. Thelogarithm of the relative concentration was then plotted for eachfraction, with results shown in FIG. 10 obtained. FIG. 10 shows thatmain nutrient ingredients of coffee can be very efficiently extracted,that is, extracted with no waste in a short time, by retrievingfractions 1 to 7, preferably fractions 2 to 7, or more preferablyfractions 2 to 5.

Furthermore, the fractions of the extract liquid obtained from thepresent test was subjected to a sensory rating by expert panelists (tenpersons). In the sensory rating, the favorableness of the flavor wasevaluated on a scale of 1 to 5 based on the mutual consent of thepanelists through a comparison with an extract liquid (control) obtainedby the conventional drip method (KALITA dripper, model number: 102D, fortwo to four persons) using 40 g of the same roasted beans as those inthe present test (roasted beans ground under the same conditions) and200 mL of hot water. The results are shown in Table 1. The resultsclearly show that a total of 40-mL fractions 2 and 3 had very excellentflavors, and even when diluted by a factor of 5, gave a better flavorthan the control extract liquid obtained by the drip method.Furthermore, the fraction 1 did not taste bad but was watery andundrinkable. The fractions 4 and 5 fell well short of the fractions 2and 3 but had a better flavor than the control. Additionally, thefractions 6 and 7 had a flavor comparable to the flavor of the control,and the other fractions had astringent ingredients and were undrinkable.Thus, it has been found that, according to the method for manufacturingaccording to the present invention, a coffee extract with a dramaticallyexcellent flavor can be obtained by retrieving the fractions 1 to 7(extraction rate of 1% to 20%), preferably the fractions 2 to 7(extraction rate of 5% to 20%), or more preferably the fractions 2 to 5(extraction rate of 5% to 15%).

The above-described results suggest that the appropriate flavoringredients of roasted coffee can be extracted separately fromastringent ingredients eluted during the latter half of the extractionand left on the tongue, by the method of carrying out the extractionwith separation according to the present invention to avoid theretrieval of the astringent ingredients. The results also suggest thatthe method allows the extraction of not only the appropriate flavoringredients of coffee but also nutrient ingredients that preventpossible lifestyle-related diseases with high efficiency.

TABLE 1 Rating Corresponding fractions Very excellent 2, 3 Excellent 4,5 Same as the drip method 6, 7 Watery and undrinkable 1 Undrinkable 8,9, 10, 11, 12

Example 1

A coffee extract was manufactured using 30-g Arabica beans grown inGuatemala and roasted and ground at the medium level. As an extractiondevice, a coffee extraction device was used which was of the same typeas that shown in FIG. 7 and in which a granule container part 2 had aninner diameter of 25 mm (this method is hereinafter referred to as a CCmethod: Column Chromatography). A flannel cloth was used as a lowerfilter member 10, and as a restraining member (upper filter member) 11,a metal mesh of about 80 m/s was used around which silicon packing wasinstalled to allow the metal mesh to tightly contact the column. Thelower filter member 10 and the restraining member 11 were positioned inabutting contact and in alignment with a lower surface and an uppersurface, respectively, of deposited layers of coffee granules. Athree-way cock 9 was operated to inject 90-mL hot water (90° C.) fromthe lower side of the apparatus to an extraction section E at SV=1. Whenthe surface of the hot water flowing upward through the coffee granulelayer comes into contact with the upper filter member 11, the cock 9 wasclosed. Subsequently, 1,200-mL hot water (90° C.) was injected towardthe extraction section E through an upper opening 2A. The resultantextract liquid was then retrieved at SV=1 at extraction rates of 10%,15%, 20% and 25%, and was evaluated for the flavor thereof. Forcomparison, a coffee extract was obtained by a unidirectional extractionmethod using the same amount of the same roasted beans (roasted beansground under the same conditions) and the coffee extraction device shownin FIG. 1 (CD method: Column Drip). Furthermore, a coffee extract wasobtained using an extraction device of a conventional drip type (KALITAdripper, model number: 102D, for two to four persons), the same amountof the same roasted beans (roasted beans ground under the sameconditions), and similar hot water (PD method: Paper Drip).

Table 2 shows the results of a sensory rating. With extraction based onthe conventional CD method and PD method, astringency or bitterness wasperceived from the initial period of the extraction. In contrast, the CCmethod according to the present invention achieved extraction so as toallow separation of astringency or bitterness perceived during theinitial period of the extraction, and produced a flavory and sweetcoffee extract. On the other hand, it has been found that no method canseparate astringency eluted during the middle and last period of theextraction, that is, when the extraction rate is about 25%, and left onthe tongue. This indicates that a reduced extraction rate is effectivein removing the astringency left on the tongue.

TABLE 2 Extrac- tion rate CC method CD method PD method 10% Tastesmoder- Tastes coarse Tastes sharply ately sweet and astringent bitterand Flavory and no Too bitter to astringent bitterness or drink Toobitter to astringency drink 15% Tastes sweet Tastes slightly Tastesbitter No bitterness less coarse and and astringent or astringencyastringent Too bitter to but clean Too bitter to drink drink 20% Tastesclean Tastes slightly Tastes bitter clean and astringent 25% Astringencyleft Astringency left Tastes bitter on tongue starts on tongue startsand astringent to be felt to be felt

Example 2

As is the case with Example 1, coffee extracts were obtained by theconventional CD method and PD method and the CC method according to thepresent invention. The coffee extracts were compared with one another interms of the amounts of caffeine and chlorogenic acid obtained per unitsolid with an extraction ratio (the ratio of the coffee extract to theextraction material=the coffee extract/extraction material) varied. Foranalysis, the coffee extracts as samples were filtered (0.45-μm filter)and subjected to HPLC analysis. HPLC analysis conditions are as follows.

HPLC conditions:

Column: TSK-gel ODS-80TsQA (4.6 mmφ×150 mm, TOSOH CORPORATION)

Mobile phase: Liquid A:water:acetonitrile:trifluoroaceticacid=900:100:0.5 Liquid B:water:acetonitrile:trifluoroaceticacid=200:800:0.5

Flow velocity: 1.0 mL/min

Column temperature: 40° C.

Gradient condition; analysis start to a lapse of 5 minutes: remains 0%on the gradient of Liquid B.

Lapse of 5 minutes to 11 minutes: increases up to 8% on the gradient ofLiquid BLapse of 11 minutes to 21 minutes: increases up to 10% on the gradientof Liquid BLapse of 21 minutes to 22 minutes: increases up to 100% on the gradientof Liquid BLapse of 22 minutes to 30 minutes: maintained at 100% on the gradient ofLiquid BLapse of 30 minutes to 31 minutes: decreases to 0% on the gradient ofLiquid B

Detection: A280 nm

The results of analysis of caffeine and chlorogenic acid are shown inFIG. 11. FIG. 11 shows values in terms of the amounts of caffeine andchlorogenic acid per soluble solid (Brix). FIG. 11 clearly shows that acoffee extract obtained by the CC method according to the presentinvention contains caffeine and chlorogenic acid similar in amounts tocaffeine and chlorogenic acid in coffee extracts obtained by theconventional PD method and CD method, without depending on theextraction ratio. The analysis results, in combination with the sensoryrating results in Example 1, suggest that the CC method according to thepresent invention allows manufacture of a coffee extract with anexcellent flavor for which excessive bitterness and astringency areselectively reduced with ingredients such as caffeine and chlorogenicacid unchanged, the ingredients contributing significantly to theflavor.

Example 3

The coffee extract manufactured by the CD method in Example 1 wastreated using an ultrafiltration membrane with a cut-off molecularweight of about 100,000 (VIVA SPIN 20 manufactured by SARTORIUS K.K.;cut-off molecular weight: 100,000), and the resultant liquid wasretrieved and compared, in terms of flavor, with the coffee extractobtained by the CC method in Example 1. The results are shown in Table3. When the coffee extract obtained by the conventional CD method wastreated by the ultrafiltration membrane, the bitterness and astringencyperceived during the initial period of the extraction were removed. Thissuggests that the CC method according to the present invention allowsefficient removal of macromolecular bitter and astringent ingredientswith a molecular weight of about 100,000 or more. As is apparent fromTable 3, the CC method according to the present invention is superior tothe CD method with the ultrafiltration membrane treatment in terms ofsweetness.

TABLE 3 Extraction rate CC method CD method 10% Tastes moderately sweetFlavory and tastes clear Flavory and tastes clear 15% Tastes sweetTastes clean and clear Tastes clean and clear 20% Tastes clean and clearTastes clean and clear 25% Starts to taste astringent Starts to tasteastringent

Example 4

As is the case with Example 1, coffee granules were placed in a granulecontainer part 2 in a substantially sealed manner, and hot water orwater was injected from the lower side of the extraction section E untilthe coffee granules were completely dipped in the water. Subsequently,hot water or water was injected through the upper opening 2A to producea coffee extract (extraction rate: 14.1%) (CC method). Furthermore, forcomparison, the same roasted coffee beans (ground under the sameconditions) were filled in a commercially available coffee dripper(manufactured by KALITA CO., LTD.), and hot water or water was injectedfrom the upper side of the coffee dripper to produce a coffee extract(extraction rate: 13.7%) (PD method). These coffee extracts weresubjected to a sensory rating by six expert panelists. The coffeeextracts were evaluated on a scale of 1 to 5 in terms of bitterness,fragrance, and taste ingredients (bitterness: bitterness decreases withincreasing scale value, fragrance: the level of fragrance increasesconsistently with scale value, and taste ingredients: the number of(favorable) taste ingredients increases consistently with scale value).

The results are shown in Table 4. The CC method according to the presentinvention removed approximately all of the bitterness and producedfavorable taste ingredients. In particular, it has been found that, whenthe temperature of water is high (about 90° C.) during steps b and c, acoffee extract can be manufactured which has a much better fragrancethan a coffee extract obtained by the conventional water drip(extraction at about 20° C. by the PD method). Furthermore, if a firstextraction (step b) and a second extraction (step c) are carried out at20° C. by the CC method, a larger amount of coffee extract can bemanufactured in a shorter time than in the case of extraction at 20° C.by the PD method. This indicates that the CC method according to thepresent invention is a high-yield method for manufacturing.

TABLE 4 Step b Step c From lower From upper Taste side to side toBitter- Fra- ingre- upper side lower side ness grance dient CC methodHot water Hot water 4 5 5 (present (about 90° C.) (about 90° C.)invention) Water Water 5 2 4 (about 20° C.) (about 20° C.) PD method —Hot water 1 5 5 (conven- (about 90° C.) tional — Water 5 2 3 technique)(about 20° C.)

Example 5

Commercially available coffee beans were coarsely ground, and 15 g ofthe ground coffee beans were used for extraction by the CC method, theCD method, and the PD method. For the CC method, the same apparatus asthat used in Example 1 (and the same lower and upper filter members asthose used in Example 1) was used, and hot water (about 90° C.) wasinjected from the lower side of the extraction section E until coffeegranules were completely dipped in the water. Then, hot water (about 90°C.) was injected through the upper opening 2A, and the resultant extractliquid was retrieved. For the CD method, coffee granules were placed inan apparatus similar to that used for the CC method, hot water (about90° C.) was injected through the upper opening 2A, and the resultantextract liquid was retrieved through the lower opening 2B. For the PDmethod, a conventional drip extractor (KALITA dripper, model number:102D, for two to four persons) was used, and coffee granules were filledinto a commercially available coffee filter (manufactured by KALITA CO.,LTD.). Hot water was injected from the upper side of the coffee filter,and the resultant extract liquid was retrieved. Table 5 shows the amountof extract liquid retrieved (the amount of extract liquid sampled: g),the Brix (%) of the extract, and the extraction rate (%) of the extractliquid (the Brix is a value measured using a digital refractometerRX-5000α manufactured by ATAGO CO., LTD.).

TABLE 5 Amount of extract Brix Extraction liquid sampled (%) rate (%)Column chromatography 40.1 5.46 14.6 Column drip 40.8 4.51 12.3 Paperdrip 40.4 5.44 14.7

Water was added to extracts obtained by the CC method, the CD method,and the PD method so as to adjust the Brix of each extract liquid to2.0%. The extracts were filtered using filter paper (no. 2), and the NTUturbidity of each of the extracts was measured using a NTU turbidimeter(2100AN) manufactured by HACH. The results are shown in FIG. 13. FIG. 13clearly shows that the extract liquid according to the present inventionhas the lowest turbidity and the highest clarity. This also suggeststhat the coffee extract according to the present invention has highpreservation stability.

Example 6

Arabica coffee beans were roasted so that the L value was 18, and wereground so that the average grain size was about 1.5 mm to produce coffeegranules. Extraction was carried out by the CC method according to thepresent invention using an extraction device shown in FIG. 7. As is thecase with Example 1, a flannel cloth was used as a lower filter member10, and as a restraining member (upper filter member) 11, a metal meshof about 80 m/s was used around which silicon packing was installed toallow the metal mesh to tightly contact the column. The lower filtermember 10 and the restraining member 11 were positioned in abuttingcontact and in alignment with a lower surface and an upper surface,respectively, of deposited layers of the coffee granules and to placethe coffee granules in a substantially sealed manner. At this time, theamount of the coffee granules was 100 g, and the cross-sectional shapeof a substantial rectangle in a direction along the axis of anextraction section E was such that the ratio (H/L) of the width (L) toheight (H) of the rectangle was about 4. A three-way cock 9 was operatedto inject 90-mL hot water (90° C.) from the lower side of the apparatusto the extraction section E at SV=1. When the surface of the hot waterflowing upward through the coffee granule layer comes into contact withthe upper filter member 11, the cock 9 was closed. Subsequently,1,200-mL hot water (90° C.) was injected toward the extraction section Ethrough an upper opening 2A, and the resultant extract liquid wasretrieved at SV=1.

Basic conditions were set as described above, and the following werevaried to be examined: the degree of grind of the coffee granules(average grain size), the shape of the extraction section, thetemperature of water injected from the first direction multiplied by SV,and the temperature of water injected from the second directionmultiplied by SV.

The results are shown in Table 6. In Table 6, circles denote a flavorequivalent to a flavor obtained under the basic conditions, and doublecircles denote a flavor better than the flavor obtained under the basicconditions.

TABLE 6 Average grain size ~0.1 ~0.5 ~1.0 ~1.5 ~2.0 of beans (mm) Δ ◯ ⊚⊚ ◯ Aspect ratio of 0.1 2 4 6 10 12 20 beans (h/w) Δ ◯ ⊚ ⊚ ◯ ◯ Δ Watertemperature 30 60 90 (° C.) ◯ ◯ ⊚ Flow from first direction Flowvelocity 3 7 10 20 30 50 100 (space velocity sv) ◯ ⊚ ⊚ ◯ ◯ ◯ ◯ Amount ofliquid 0.3 0.5 1 1.5 2 transferred (bean volume ratio) ◯ ⊚ ⊚ ◯ Δ Flowfrom second direction Flow velocity 3 7 10 20 30 50 100 (space velocitysv) ◯ ⊚ ⊚ ◯ ◯ ◯ ◯ Amount of liquid 0.3 0.5 1 1.5 2 3 5 transferred (beanvolume ratio) ◯ ⊚ ⊚ ⊚ ⊚ ◯ Δ

Example 7

A coffee extraction device 1 was used which was similar to the coffeeextraction device used in Test Example 1. Thirty-gram Robusta coffeebeans grown in Indonesia and roasted in a French manner were ground atthe medium level, and the ground coffee beans were placed in a granulecontainer part 2. With a three-way cock 9 closed, 100-mL hot water (95°C.) was injected into a hot water container 4. A lower tip of the hotwater container 4 was fitted into an upper end (the position of arestraining member 11) of an extraction section E, and an operation ofopening the three-way cock 9 was performed to inject hot water into theextraction section E through a lower opening 2B. When a surface of thehot water flowing upward through the granule layer in the extractionsection E passes through the restraining member 11 and reaches aposition 10 mm above the restraining member 11, the cock 9 was closed.Subsequently, 350-mL hot water was injected through an upper opening 2Ain the granule container part, the cock 9 was opened, and a colorlessportion and a faint yellow portion of an outflow liquid (extractionrate: about 1%) were disposed of. When the outflow liquid turnedbrownish, the outflow liquid started to be retrieved with the flavorthereof checked. When the outflow liquid became cervine and the colorwas subsequently lightened again, the outflow liquid continued to beretrieved with the flavor thereof similarly checked until the “veryexcellent” fractions completed flowing out. Then, the retrievalcontainer was changed, and the retrieval was continued. When the“excellent” fractions completed flowing out, the retrieval was ended.The amount of extract liquid retrieved was 60 mL for the “veryexcellent” fractions (Extract 1 according to the present invention) and40 mL for the “excellent” fractions (Extract 2 according to the presentinvention).

For comparison, extraction was carried out on the same roasted beans asthose in the Example 7 (roasted beans ground under the same conditions)by the drip method (KALITA dripper, model number: 102D, for two to fourpersons) using 350-mL hot water (95° C.) so that the extraction rate wasabout 15% (Comparative Example 1). Six expert panelists compared, interms of flavor, Comparative Example 1 with each of Extract 1 accordingto the present invention, Extract 2 according to the present invention,and a mixture of a total amount of Extracts 1 and 2 according to thepresent invention (Extract 3 according to the present invention). Allthe panelists determined that all of Extracts 1 to 3 according to thepresent invention has much better flavors than Comparative Example 1.Extracts 1 to 3 according to the present invention were thick andflavory coffee liquids without excessively strong bitterness and had avery clean aftertaste and no astringent aftertaste left on the tongue,and were thus coffee with an excellent flavor.

Example 8

A coffee extract was manufactured in a manner similar to the manner ofExample 7 except that 30-g each of granules were obtained by roasting,in an Italian manner, Arabica coffee beans grown in Indonesia and havingthe lowest market price and then grinding the roasted beans at themedium level and that a different amount of extraction solvent wasinjected from the lower side of an extraction section E. The amount ofextraction solvent was set in two ways: the amount needed for a surfaceof hot water flowing upward through the granule layer in the extractionsection E to come into contact with the restraining member 11 and theamount needed for the surface of the hot water flowing upward throughthe granule layer in the extraction section E to pass through therestraining member 11 and reach a position 10 mm above the restrainingmember 11. Six expert panelists evaluated the flavor of a retrievedliquid and all of the panelists determined that the bitterness andastringency were significantly suppressed, making the coffee extracttasty.

Example 9

Thirty grams of commercially available brand coffee beans shown to havebeen roasted at the highest level for iced coffee were ground at themedium level. A technique similar to the technique in Example 7 was usedto carry out extraction on the ground beans to obtain a 60-mL “veryexcellent” coffee extract and a 40-mL “excellent” coffee extract. The60-mL “very excellent” coffee extract was diluted to 300 mL with coldwater, and the diluted coffee extract was cooled in a refrigerator (5°C.) (Extract 4 according to the present invention).

For comparison, 30 g of the same coffee granules as those used inExample 9 were placed in a French press coffee pot manufactured by Bodum(500-mL type), and hot water at 95° C. was injected into the Frenchpress coffee pot. Four minutes later, an extract liquid was separatedfrom the liquid to produce 300 mL of coffee extract, which was thencooled in the refrigerator (5° C.) (Comparative Example 2). Extract 4according to the present invention and Comparative Example 2 wereevaluated for flavor by six exert panelists. Iced coffee correspondingto Extract 4 according to the present invention was tasty coffee havingmoderate bitterness and a rich fragrance even when drunk black. Incontrast, Comparative Example 2 was very bitter and did not tastedirectly drinkable.

Example 10

As an extraction device, a coffee extraction device was used whichincluded a substantially cylindrical glass pipe (inner diameter: 50 mmand length: 150 mm) having an upper opening and a lower opening (2A and2B) and serving as a granule container part 2 as shown in FIG. 9. Thelower opening 2B in the granule container part 2 included an extractionpipe (glass pipe/chromatography pipe) with a two-way cock 9′. The samelower filter member 10 as that used in Example 7 was installed, and 30 gof coffee granules obtained by roasting, in an Italian manner, Arabicacoffee beans grown in Ethiopia and grinding the roasted coffee beans atthe medium level were placed on an upper surface of the lower filtermember. A restraining member 11 with an outer diameter of 54 mm wasinstalled on the coffee granules and included an O ring formed of wirewith a diameter of 1 mm and having a diameter of 40 mm and sewed on fouroverlapping lint clothes. A safety pipetter 13 was installed above thegranule container part 2 via a joint 12. A beaker with 50-mL hot water(95° C.) was placed at a retrieval port 8 at the lower part of thegranule container part 2. The retrieval port 8 was inserted into the hotwater, and the two-way cock 9′ and the safety pipetter 13 were operatedto suck the hot water up to an upper end of an extraction section E.Then, the two-way cock 9′ was closed, and the safety pipetter 13 wasremoved. One hundred-mL hot water (about 90° C.) was injected into theextraction section E through an upper opening 2A of the granulecontainer part 2. The safety pipetter 13 was installed again, and airpressure is applied to the granule container part 2. Then, the two-waycock 9′ was opened, the first 10 mL of outflow liquid was disposed of,and the next 60 mL of outflow liquid was retrieved. The flavor of theretrieved liquid was checked and determined to belong to the “veryexcellent” class.

1. A method for manufacturing a coffee extract, the method comprising:a) a step of placing coffee granules in a granule container partsubstantially sealed by a restraining member; b) a step of guiding anextraction solvent from a first direction into the granule containerpart for extraction; and c) a step of retrieving, from the firstdirection, a coffee extract stored in the granule container part.
 2. Themethod according to claim 1, wherein, in step c), the coffee extract isretrieved by guiding water from a second direction opposite to the firstdirection.
 3. The method according to claim 1, wherein, in step c), thecoffee extract is retrieved in such a manner that an extraction rate is20% or less.
 4. The method according to claim 1, wherein the restrainingmember is a mesh member.
 5. The method according to claim 1, wherein thecoffee granules are accommodated so as to accumulate in such a mannerthat the coffee granules have a substantially rectangularcross-sectional shape in a direction along an axis.
 6. The methodaccording to claim 1, wherein the restraining member is positioned inabutting contact with or in close proximity to a surface of depositedlayers of the coffee granules which is opposite to the first direction.7. The method according to claim 1, wherein the first direction is on alower side of the deposited layers of the coffee granules.
 8. The methodaccording to claim 1, wherein, in step b), the extraction solvent isinjected up to a position substantially aligning with a top surface ofthe deposited layers of coffee granules.